Camshaft adjustment devices, in particular those which operate hydraulically, are generally used in internal combustion engines. Examples thereof are disclosed by DE 198 29 049 A1 and U.S. Pat. No. 5,931,126. If the camshaft adjuster operates hydraulically—which is typical—it has an impeller in which blades are formed or arranged. The blades are located in hydraulic chambers which are incorporated in an external rotor. By the particular side of the hydraulic chambers being correspondingly acted upon by hydraulic fluid, the internal rotor (connected to the camshaft) can be adjusted relative to the external rotor between an “early stop” and a “late stop”. In this case, the flow of hydraulic oil is controlled by an electrically activated directional control valve. The rotational movement of the crankshaft is generally transmitted to the external rotor via a gearwheel to which the external rotor is connected for conjoint rotation.
The camshaft adjuster therefore has a drive element which is driven by the crankshaft and is connected to a housing element in which the adjustment mechanism is arranged. During the operation of the internal combustion engine, the drive element, which is frequently driven by a chain or by a drive gearwheel, together with the housing element, rotate about an axis at the rotational speed of the camshaft. In this case, the camshaft adjuster is, however, partially surrounded by a housing (or by a housing bell) of the internal combustion engine.
In the housing bell, oil is poured to a desired oil level at which the camshaft adjuster runs. At too low a circulation of the oil, dirt particles are disadvantageously deposited in the housing bell, which may even result in failure of the camshaft adjuster.